Internormen Filters Private Ltd. Offers Directly Mounted Return Line Filter. Internormen Filters Private Ltd. Is an ISO 9001: 2000 accredited company supplying a wide range of filters for hydraulic and lubricating fluids and contamination monitoring system. The Directly Mounted Return Line Filter of TRW series model is suitable for a working pressure up to 10 bar and can be directly mounted to the reservoir and connected to the return-line. The Directly Mounted Return Line Filter can be used for petroleum-based fluids, HW emulsions, water glycols, most synthetic fluids and lubrication fluids.